$\dfrac{9}{10} + \dfrac{2}{4} = {?}$
Answer: ${\dfrac{9}{10}}$ ${\dfrac{2}{4}}$ $+$ ${\dfrac{9 \times 2}{10 \times 2}}$ ${\dfrac{2 \times 5}{4 \times 5}}$ $+$ ${\dfrac{18}{20}}$ ${\dfrac{10}{20}}$ $+$ $ = \dfrac{{18} + {10}}{20} $ $ = \dfrac{28}{20}$